Attention and Regional Gray Matter Development in Very Preterm Children at Age 12 Years

Timed fetal inflammation and postnatal hypoxia cause cortical white matter injury, interneuron imbalances, and behavioral deficits in a double-hit rat model of encephalopathy of prematurity

Extreme preterm birth-associated adversities are a major risk factor for aberrant brain development, known as encephalopathy of prematurity (EoP), which can lead to long-term neurodevelopmental impairments. Although progress in clinical care for preterm infants has markedly improved perinatal outcomes, there are currently no curative treatment options available to combat EoP. EoP has a multifactorial etiology, including but not limited to pre- or postnatal immune activation and oxygen fluctuations. Elucidating the underlying mechanisms of EoP and determining the efficacy of potential therapies relies on valid, clinically translatable experimental models that reflect the neurodevelopmental and pathophysiological hallmarks of EoP. Here, we expand on our double-hit rat model that can be used to study EoP disease mechanisms and therapeutic options in a preclinical setting. Pregnant Wistar dams were intraperitoneally injected with 10 μg/kg LPS on embryonic day (E)20 and offspring was subjected to hypoxia (140 min, 8% O2) at postnatal day 4. Rats exposed to fetal inflammation and postnatal hypoxia (FIPH) showed neurodevelopmental impairments, such as reduced nest-seeking ability, ultrasonic vocalizations, social engagement, and working memory, and increased anxiety and sensitivity. Impairments in myelination, oligodendrocyte maturation and interneuron development were examined as hallmarks for EoP, in different layers and coordinates of the cortex using histological and molecular techniques. Myelin density and complexity was decreased in the cortex, which partially coincided with a decrease in mature oligodendrocytes. Furthermore, interneuron populations (GAD67+ and PVALB+) were affected. To determine if the timing of inducing fetal inflammation affected the severity of EoP hallmarks in the cortex, multiple timepoints of fetal inflammation were compared. Inflammation at E20 combined with postnatal hypoxia gave the most severe EoP phenotype in the cortex. In conclusion, we present a double-hit rat model which displays various behavioral, anatomical and molecular hallmarks of EoP, including diffuse white matter injury. This double-hit model can be used to investigate pathophysiological mechanisms and potential therapies for EoP.

Children born very preterm experience altered cortical expansion over the first decade of life

The brain develops rapidly from the final trimester of gestation through childhood, with cortical surface area expanding greatly in the first decade of life. However, it is unclear exactly where and how cortical surface area changes after birth, or how prematurity affects these developmental trajectories. Fifty-two very preterm (gestational age at birth = 26 ± 1.6 weeks) and 41 full-term (gestational age at birth = 39 ± 1.2 weeks) infants were scanned using structural magnetic resonance imaging at term-equivalent age and again at 9/10 years of age. Individual cortical surface reconstructions were extracted for each scan. Infant and 9/10 cortical surfaces were aligned using anatomically constrained Multimodal Surface Matching (aMSM), a technique that allows calculation of local expansion gradients across the cortical surface for each individual subject. At the neonatal time point, very preterm infants had significantly smaller surface area than their full-term peers (P < 0.001), but at the age 9/10-year time point, very preterm and full-term children had comparable surface area (P > 0.05). Across all subjects, cortical expansion by age 9/10 years was most pronounced in frontal, temporal, and supramarginal/inferior parietal junction areas, which are key association cortices (P Spin < 0.001). Very preterm children showed greater cortical surface area expansion between term-equivalent age and age 9/10 compared to their full-term peers in the medial and lateral frontal areas, precuneus, and middle temporal/banks of the superior sulcus junction (P < 0.05). Furthermore, within the very preterm group, expansion was highly variable within the orbitofrontal cortex and posterior regions of the brain. By mapping these patterns across the cortex, we identify differences in association cortices that are known to be important for executive functioning, emotion processing, and social cognition. Additional longitudinal work will be needed to understand if increased expansion in very preterm children is adaptive, or if differences persist into adulthood.

Neurobiological perspective on the development of executive functions

Executive functions are a set of top-down cognitive processes necessary for emotional self-regulation and goal-directed behaviour supporting, among others, academic abilities. Premature infants are at high risk for subsequent cognitive, psychosocial, or behavioural problems even in the absence of medical complications and in spite of normal brain imaging. Given that this is a sensitive period of brain growth and maturation, these factors may place preterm infants at high risk for executive function dysfunction, disrupted long-term development, and lower academic achievements. Therefore, careful attention to interventions at this age is essential for intact executive functions and academic development.

Visuospatial working memory of children and adults born very preterm and/or very low birth weight

BACKGROUND

This paper examines the visuospatial working memory (WM) performance of children and adults born very preterm (VPT) and/or very low birth weight (VLBW) relative to their full-term (FT)-born peers. Of interest was the nature and severity of observed impairments, as well associations with educational/occupational functioning at each age point.

METHODS

Participants were drawn from two prospective cohort studies: (1) a regional cohort of 110 VPT (<32 weeks' gestation and <1500 g) and 113 FT born children assessed at age 12 years; (2) a national cohort of 229 VLBW (<1500 g) and 100 FT born adults assessed at age 28 years. Visuospatial WM was assessed using a four-span/difficulty-level computerized task.

RESULTS

Both children and adults born VPT/VLBW had poorer visuospatial WM than FT controls, with their performance less accurate, slower (correct trials), and less efficient with increasing task difficulty (Cohen's d = 0.27-0.51; p < 0.05). Adults had better visuospatial WM than children, but between-group differences were highly similar across ages, before and after adjustment for confounding social background and individual factors. Poorer WM was associated with lower levels of educational and occupational/socioeconomic achievement.

CONCLUSIONS

Visuospatial WM difficulties persist into adulthood raising concerns for the longer-term cognitive and adaptive functioning of VPT survivors.

IMPACT

Both children and adults born very preterm have poorer visuospatial working memory than their term-born peers. They are less accurate, take longer to respond correctly and are less efficient, with test performance declining with increasing cognitive demand. Similar differences in visuospatial working memory are observed between VPT/VLBW and full-term individuals during both childhood and adulthood, with these differences remaining even after covariate adjustment. Individuals with poorer visuospatial working memory have lower levels of educational achievement and occupational/socioeconomic success. Visuospatial working memory difficulties persist into adulthood and appear to continue to impact everyday functioning and life-course opportunities.

Individual Attention Patterns in Children Born Very Preterm and Full Term at 7 and 13 Years of Age

OBJECTIVE

To identify attention profiles at 7 and 13 years, and transitions in attention profiles over time in children born very preterm (VP; <30 weeks' gestation) and full term (FT), and examine predictors of attention profiles and transitions.

METHODS

Participants were 167 VP and 60 FT children, evaluated on profiles across five attention domains (selective, shifting and divided attention, processing speed, and behavioral attention) at 7 and 13 years using latent profile analyses. Transitions in profiles were assessed with contingency tables. For VP children, biological and social risk factors were tested as predictors with a multinomial logistic regression.

RESULTS

At 7 and 13 years, three distinct profiles of attentional functioning were identified. VP children were 2-3 times more likely to show poorer attention profiles compared with FT children. Transition patterns between 7 and 13 years were stable average, stable low, improving, and declining attention. VP children were two times less likely to have a stable average attention pattern and three times more likely to have stable low or improving attention patterns compared with FT children. Groups did not differ in declining attention patterns. For VP children, brain abnormalities on neonatal MRI and greater social risk at 7 years predicted stable low or changing attention patterns over time.

CONCLUSIONS

VP children show greater variability in attention profiles and transition patterns than FT children, with almost half of the VP children showing adverse attention patterns over time. Early brain pathology and social environment are markers for attentional functioning.

Associations Between Neonatal Brain Structure, the Home Environment, and Childhood Outcomes Following Very Preterm Birth

Background

Very preterm birth is associated with an increased risk of childhood psychopathology and cognitive deficits. However, the extent to which these developmental problems associated with preterm birth are amenable to environmental factors or determined by neurobiology at birth remains unclear.

Methods

We derived neonatal brain structural covariance networks using non-negative matrix factorization in 384 very preterm infants (median gestational age [range], 30.29 [23.57–32.86] weeks) who underwent magnetic resonance imaging at term-equivalent age (median postmenstrual age, 42.57 [37.86–44.86] weeks). Principal component analysis was performed on 32 behavioral and cognitive measures assessed at preschool age (n = 206; median age, 4.65 [4.19–7.17] years) to identify components of childhood psychopathology and cognition. The Cognitively Stimulating Parenting Scale assessed the level of cognitively stimulating experiences available to the child at home.

Results

Cognitively stimulating parenting was associated with reduced expression of a component reflecting developmental psychopathology and executive dysfunction consistent with the preterm phenotype (inattention-hyperactivity, autism spectrum behaviors, and lower executive function scores). In contrast, a component reflecting better general cognitive abilities was associated with larger neonatal gray matter volume in regions centered on key nodes of the salience network, but not with cognitively stimulating parenting.

Conclusions

Our results suggest that while neonatal brain structure likely influences cognitive abilities in very preterm children, the severity of behavioral symptoms that are typically observed in these children is sensitive to a cognitively stimulating home environment. Very preterm children may derive meaningful mental health benefits from access to cognitively stimulating experiences during childhood.

Exploring predictors at toddler age of distinct profiles of attentional functioning in 6-year-old children born moderate-to-late preterm and full term

OBJECTIVE

Examining relationships of toddler abilities in attention, cognitive, motor, and language development, and behavioral problems, with distinct attention profiles at 6 years of age in children born moderate-to-late preterm and full term.

METHOD

Longitudinal study with a cohort of 88 moderate-to-late preterm and 83 full term born children. At 18 months attention abilities were assessed. At 24 months cognitive, motor, and language development was examined and behavioral problems were screened. At 6 years ten measures of attention were administered, which were used to classify children in one of four attentional functioning profiles (normal attention, overall poorer attention, poorer cognitive attention, and behavioral attention problems). Performance at 18 and 24 months was examined in relation to these four distinct attention profiles, as well as in relation to normal (first profile) versus subaverage attention (second, third, and fourth profiles) using multinomial logistic regressions.

RESULTS

Orienting and alerting attention, and receptive language were related to distinct attention profiles. Specifically, children with an overall poorer attention profile at 6 years were differentiated by lower orienting attention and receptive language scores at toddler age, while those with a poorer cognitive attention profile showed lower early alerting attention at 18 months. Children with a behavioral attention problems profile at 6 years were differentiated by lower orienting attention but higher alerting attention scores at toddler age. Orienting attention and receptive language, but not alerting attention, at toddler age were related to normal versus subaverage attention, with lower scores predicting subaverage attention.

CONCLUSIONS

Children at risk of poorer attentional functioning at school-age, expressed in distinct attention profiles, already showed differentiated functioning in attention abilities and in language comprehension as toddlers. Distinguishing distinct attention profiles could be important for future research and clinical practice, as is early monitoring of attention and language abilities in children at risk.

Distinct Profiles of Attention in Children Born Moderate-to-Late Preterm at 6 Years

Objective

Attention difficulties are commonly reported by caregivers in school-aged children born moderate-to-late preterm (MLPT; 32–36 weeks’ gestation). We aimed to assess distinct aspects of attentional functioning (i.e. orienting, alerting and executive attention, processing speed and behavioral components) in children born MLPT and full term (FT), profiles of attentional functioning, and associated risk factors such as preterm birth.

Methods

Participants were 170 (87 MLPT and 83 FT) children, evaluated on cognitive and behavioral attention aspects at 6 years of age. We used a variable-centered approach to compare attentional functioning of children born MLPT and FT at group level, and a person-centered approach to identify profiles of attentional functioning. Neonatal and demographic characteristics of these profiles were compared.

Results

The variable-centered approach showed that at group level children born MLPT had poorer orienting attention and processing speed, and behavioral attention than children born FT. The person-centered approach revealed four profiles: (a) normal attentional functioning, (b) overall poorer attention, (c) poorer cognitive attention, and (d) behavioral attention problems. Children born MLPT were overrepresented in each of the suboptimal attention profiles, and were more dispersed across profiles than children born FT.

Conclusions

Children born MLPT are at increased risk of difficulties in some attention aspects, but at group level differences with children born FT are small. However, children born MLPT show considerable variation in the nature of attention difficulties and are twice as likely to show a suboptimal attention profile, indicating a cumulation of poorer attention scores.

Functional Connectivity Network Disruption Underlies Domain-Specific Impairments in Attention for Children Born Very Preterm

Attention problems are common in school-age children born very preterm (VPT; < 32 weeks gestational age), but the contribution of aberrant functional brain connectivity to these problems is not known. As part of a prospective longitudinal study, brain functional connectivity (fc) was assessed alongside behavioral measures of selective, sustained, and executive attention in 58 VPT and 65 full-term (FT) born children at corrected-age 12 years. VPT children had poorer sustained, shifting, and divided attention than FT children. Within the VPT group, poorer attention scores were associated with between-network connectivity in ventral attention, visual, and subcortical networks, whereas between-network connectivity in the frontoparietal, cingulo-opercular, dorsal attention, salience and motor networks was associated with attention functioning in FT children. Network-level differences were also evident between VPT and FT children in specific attention domains. Findings contribute to our understanding of fc networks that potentially underlie typical attention development and suggest an alternative network architecture may help support attention in VPT children.

Executive function deficits mediate the association between very preterm birth and behavioral problems at school-age

BACKGROUND & AIMS

Children and adolescents born very preterm are at increased risk to develop executive function deficits and to suffer from social, emotional and attentional problems. This study investigated whether executive function deficits contribute to behavioral problems in children and adolescents born very preterm at school-age.

STUDY DESIGN

Thirty-eight children and adolescents born very preterm and 41 age-matched term-born peers were assessed at a mean age of 12.9 (±1.8) years with a comprehensive battery of executive function tests, including working memory, planning, cognitive flexibility, and verbal fluency. A composite score was calculated to reflect overall executive function abilities. To assess behavioral problems, parents completed the Strengths and Difficulties Questionnaire (SDQ). Mediation analysis was applied to quantify the effect of preterm birth on behavioral problems with executive function abilities as a mediating variable.

RESULTS

Executive function abilities were poorer in the very preterm compared to the term-born group (d = 0.62, p = .005) and the parents of very preterm children reported more behavioral problems on the SDQ Total Difficulties Score (d = 0.54, p = .01). The effect of birth status on behavioral problems was significantly mediated by executive function abilities while adjusting for age at assessment, sex, and socioeconomic status (F(2, 76) = 6.42, p = .002, R² = 0.14).

CONCLUSION

Results from this study suggest that the increase in behavioral symptoms in very preterm children at school-age compared to term-born peers may partly be explained by their executive function deficits. These findings highlight the importance of continuously monitoring the development of children born very preterm to provide optimal care as they grow up.

Impact of prematurity on neurodevelopment

The consequences of prematurity on brain functional development are numerous and diverse, and impact all brain functions at different levels. Prematurity occurs between 22 and 36 weeks of gestation. This period is marked by extreme dynamics in the physiologic maturation, structural, and functional processes. These different processes appear sequentially or simultaneously. They are dependent on genetic and/or environmental factors. Disturbance of these processes or of the fine-tuning between them, when caring for premature children, is likely to induce disturbances in the structural and functional development of the immature neural networks. These will appear as impairments in learning skills progress and are likely to have a lasting impact on the development of children born prematurely. The level of severity depends on the initial alteration, whether structural or functional. In this chapter, after having briefly reviewed the neurodevelopmental, structural, and functional processes, we describe, in a nonexhaustive manner, the impact of prematurity on the different brain, motor, sensory, and cognitive functions.

Toddler skills predict moderate-to-late preterm born children's cognition and behaviour at 6 years of age

OBJECTIVE

To compare moderate-to-late preterm born (32-36 weeks' gestation) to full term born (≥37 weeks' gestation) children in cognitive and behavioural functioning at the age of 6 years and assess which toddler skills predict later cognitive and behavioural functioning.

DESIGN

A prospective longitudinal study with a cohort of 88 moderate-to-late preterm and 83 full term born Dutch children, followed from 18 months to 6 years of age. Orienting, alerting and executive attention skills were assessed at 18 months (corrected for prematurity), and cognitive, motor and language skills (Bayley-III-NL) at 24 months (corrected for prematurity). At 6 years (corrected for prematurity), cognitive (indices of IQ; WPPSI-III-NL) and behavioural functioning (CBCL/6-18) were assessed. Group differences and potential predictors were examined with MANCOVAs and hierarchical regression analyses.

RESULTS

At 6 years, moderate-to-late preterm born children performed poorer than full term born children on cognitive processing speed, and they showed more behavioural attention problems. Attention problems at 6 years were predicted by poorer orienting attention skills at 18 months, while lower performance IQ was predicted by poorer alerting attention skills at 18 months. Full Scale IQ and Verbal IQ at 6 years were predicted by language skills at 24 months. Moderate-to-late preterm and full term born children showed some differing correlational patterns in the associations between early skills and later functioning, although in further analyses predictors appeared the same for both groups.

CONCLUSIONS

Moderate-to-late preterm born children show specific vulnerabilities at primary school-age, particularly in cognitive processing speed and behavioural attention problems. Cognitive and behavioural functioning at 6 years can be predicted by differentiated attention skills at 18 months and language skills at 24 months.

Prefrontal Cortex Dopamine Transporter Gene Network Moderates the Effect of Perinatal Hypoxic-Ischemic Conditions on Cognitive Flexibility and Brain Gray Matter Density in Children

BACKGROUND

Genetic polymorphisms of the dopamine transporter gene (DAT1) and perinatal complications associated with poor oxygenation are risk factors for attentional problems in childhood and may show interactive effects.

METHODS

We created a novel expression-based polygenic risk score (ePRS) reflecting variations in the function of the DAT1 gene network (ePRS-DAT1) in the prefrontal cortex and explored the effects of its interaction with perinatal hypoxic-ischemic-associated conditions on cognitive flexibility and brain gray matter density in healthy children from two birth cohorts-MAVAN from Canada (n = 139 boys and girls) and GUSTO from Singapore (n = 312 boys and girls).

RESULTS

A history of exposure to several perinatal hypoxic-ischemic-associated conditions was associated with impaired cognitive flexibility only in the high-ePRS group, suggesting that variation in the prefrontal cortex expression of genes involved in dopamine reuptake is associated with differences in this behavior. Interestingly, this result was observed in both ethnically distinct birth cohorts. Additionally, parallel independent component analysis (MAVAN cohort, n = 40 children) demonstrated relationships between single nucleotide polymorphism-based ePRS and gray matter density in areas involved in executive (cortical regions) and integrative (bilateral thalamus and putamen) functions, and these relationships differ in children from high and low exposure to hypoxic-ischemic-associated conditions.

CONCLUSIONS

These findings reveal that the impact of conditions associated with hypoxia-ischemia on brain development and executive functions is moderated by genotypes associated with dopamine signaling in the prefrontal cortex. We discuss the potential impact of innovative genomic and environmental measures for the identification of children at high risk for impaired executive functions.

Interneuron Development Is Disrupted in Preterm Brains With Diffuse White Matter Injury: Observations in Mouse and Human

Preterm brain injury, occurring in approximately 30% of infants born <32 weeks gestational age, is associated with an increased risk of neurodevelopmental disorders, such as autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). The mechanism of gray matter injury in preterm born children is unclear and likely to be multifactorial; however, inflammation, a high predictor of poor outcome in preterm infants, has been associated with disrupted interneuron maturation in a number of animal models. Interneurons are important for regulating normal brain development, and disruption in interneuron development, and the downstream effects of this, has been implicated in the etiology of neurodevelopmental disorders. Here, we utilize postmortem tissue from human preterm cases with or without diffuse white matter injury (WMI; PMA range: 23⁺² to 28⁺¹ for non-WMI group, 26⁺⁶ to 30⁺⁰ for WMI group, p = 0.002) and a model of inflammation-induced preterm diffuse white matter injury (i.p. IL-1β, b.d., 10 μg/kg/injection in male CD1 mice from P1–5). Data from human preterm infants show deficits in interneuron numbers in the cortex and delayed growth of neuronal arbors at this early stage of development. In the mouse, significant reduction in the number of parvalbumin-positive interneurons was observed from postnatal day (P) 10. This decrease in parvalbumin neuron number was largely rectified by P40, though there was a significantly smaller number of parvalbumin positive cells associated with perineuronal nets in the upper cortical layers. Together, these data suggest that inflammation in the preterm brain may be a contributor to injury of specific interneuron in the cortical gray matter. This may represent a potential target for postnatal therapy to reduce the incidence and/or severity of neurodevelopmental disorders in preterm infants.

A machine learning investigation of volumetric and functional MRI abnormalities in adults born preterm

Imaging studies have characterized functional and structural brain abnormalities in adults after premature birth, but these investigations have mostly used univariate methods that do not account for hypothesized interdependencies between brain regions or quantify accuracy in identifying individuals. To overcome these limitations, we used multivariate machine learning to identify gray matter volume (GMV) and amplitude of low frequency fluctuations (ALFF) brain patterns that best classify young adults born very preterm/very low birth weight (VP/VLBW; n = 94) from those born full-term (FT; n = 92). We then compared the spatial maps of the structural and functional brain signatures and validated them by assessing associations with clinical birth history and basic cognitive variables. Premature birth could be predicted with a balanced accuracy of 80.7% using GMV and 77.4% using ALFF. GMV predictions were mediated by a pattern of subcortical and middle temporal reductions and volumetric increases of the lateral prefrontal, medial prefrontal, and superior temporal gyrus regions. ALFF predictions were characterized by a pattern including increases in the thalamus, pre- and post-central gyri, and parietal lobes, in addition to decreases in the superior temporal gyri bilaterally. Decision scores from each classification, assessing the degree to which an individual was classified as a VP/VLBW case, were predicted by the number of days in neonatal hospitalization and birth weight. ALFF decision scores also contributed to the prediction of general IQ, which highlighted their potential clinical significance. Combined, the results clarified previous research and suggested that primary subcortical and temporal damage may be accompanied by disrupted neurodevelopment of the cortex.

Altered grey matter volume, perfusion and white matter integrity in very low birthweight adults

This study examined the long-term effects of being born very-low-birth-weight (VLBW, <1500 g) on adult cerebral structural development using a multi-method neuroimaging approach. The New Zealand VLBW study cohort comprised 413 individuals born VLBW in 1986. Of the 338 who survived to discharge, 229 were assessed at age 27–29 years. Of these, 150 had a 3 T MRI scan alongside 50 healthy term-born controls. The VLBW group included 53/57 participants born <28 weeks gestation. MRI analyses included: a) structural MRI to assess grey matter (GM) volume and cortical thickness; b) arterial spin labelling (ASL) to quantify GM perfusion; and c) diffusion tensor imaging (DTI) to measure white matter (WM) integrity. Compared to controls, VLBW adults had smaller GM volumes within frontal, temporal, parietal and occipital cortices, bilateral cingulate gyri and left caudate, as well as greater GM volumes in frontal, temporal and occipital areas. Thinner cortex was observed within frontal, temporal and parietal cortices. VLBW adults also had less GM perfusion within limited temporal areas, bilateral hippocampi and thalami. Finally, lower fractional anisotropy (FA) and axial diffusivity (AD) within principal WM tracts was observed in VLBW subjects. Within the VLBW group, birthweight was positively correlated with GM volume and perfusion in cortical and subcortical regions, as well as FA and AD across numerous principal WM tracts. Between group differences within temporal cortices were evident across all imaging modalities, suggesting that the temporal lobe may be particularly susceptible to disruption in development following preterm birth. Overall, findings reveal enduring and pervasive effects of preterm birth on brain structural development, with individuals born at lower birthweights having greater long-term neuropathology.

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Very-low-birth-weight adults had smaller GM volumes and thinner cortex than controls.

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VLBW adults also showed regions of larger grey matter volumes and thicker cortex.

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Several small regions showed lower cerebral perfusion in VLBW adults than in controls.

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Diffusion tensor MRI suggested poorer WM integrity in VLBW adults than in controls.

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Within VLBW adults, all MRI measures showed positive associations with birthweight.

Aberrant structural and functional connectivity and neurodevelopmental impairment in preterm children

Background

Despite advances in antenatal and neonatal care, preterm birth remains a leading cause of neurological disabilities in children. Infants born prematurely, particularly those delivered at the earliest gestational ages, commonly demonstrate increased rates of impairment across multiple neurodevelopmental domains. Indeed, the current literature establishes that preterm birth is a leading risk factor for cerebral palsy, is associated with executive function deficits, increases risk for impaired receptive and expressive language skills, and is linked with higher rates of co-occurring attention deficit hyperactivity disorder, anxiety, and autism spectrum disorders. These same infants also demonstrate elevated rates of aberrant cerebral structural and functional connectivity, with persistent changes evident across advanced magnetic resonance imaging modalities as early as the neonatal period. Emerging findings from cross-sectional and longitudinal investigations increasingly suggest that aberrant connectivity within key functional networks and white matter tracts may underlie the neurodevelopmental impairments common in this population.

Main body

This review begins by highlighting the elevated rates of neurodevelopmental disorders across domains in this clinical population, describes the patterns of aberrant structural and functional connectivity common in prematurely-born infants and children, and then reviews the increasingly established body of literature delineating the relationship between these brain abnormalities and adverse neurodevelopmental outcomes. We also detail important, typically understudied, clinical, and social variables that may influence these relationships among preterm children, including heritability and psychosocial risks.

Conclusion

Future work in this domain should continue to leverage longitudinal evaluations of preterm infants which include both neuroimaging and detailed serial neurodevelopmental assessments to further characterize relationships between imaging measures and impairment, information necessary for advancing our understanding of modifiable risk factors underlying these disorders and best practices for improving neurodevelopmental trajectories in this high-risk clinical population.

Social Adversity and Cognitive, Language, and Motor Development of Very Preterm Children from 2 to 5 Years of Age

OBJECTIVE

To assess the extent to which social and family factors explain variability in cognitive, language, and motor development among very preterm (<30 weeks of gestation) children from 2 to 5 years of age.

STUDY DESIGN

As part of a longitudinal study, very preterm children recruited as neonates were assessed at 2 (n = 87) and 5 (n = 83) years of age using standardized tests of cognitive, language, and motor ability alongside demographically matched full term (FT) children (n = 63). For very preterm children, developmental change scores were calculated for each domain to assess within-individual variability to 5 years of age. Multivariate regression and mixed-effect models examined social risk index, parenting stress, family functioning, and maternal intellectual ability as predictors of developmental variation among very preterm children.

RESULTS

Very preterm children demonstrated poorer cognitive, language, and motor abilities than FT children at 2 (P ≤ .001) and 5 (P < .002) years of age. Social adversity was associated with cognitive (P < .001) and language (P < .001) outcomes at both ages, with parenting stress also related to cognitive outcomes (P = .03). Infant medical risk was associated with motor outcome at 5 years (P=.01). Very preterm children showed considerable within-individual variation between assessments. Among very preterm children, neonatal white matter abnormalities predicted worsening cognitive (P=.04) and motor development (P = .01). Social risk index predicted worsening language development (P = .04), but this association was subsequently explained by dysfunctional maternal affective involvement (P = .01) and lower maternal intellectual ability (P = .05).

CONCLUSIONS

Both clinical and socioenvironmental factors are associated with cognitive, language, and motor developmental variation among very preterm children from infancy to early school age.

Brain gray and white matter abnormalities in preterm-born adolescents: A meta-analysis of voxel-based morphometry studies

Introduction

Studies using voxel-based morphometry report variable and inconsistent abnormalities of gray matter volume (GMV) and white matter volume (WMV) in brains of preterm-born adolescents (PBA). In such circumstances a meta-analysis can help identify the most prominent and consistent abnormalities.

Method

We identified 9 eligible studies by systematic search of the literature up to October 2017. We used Seed-based d Mapping to analyze GMV and WMV alterations between PBA and healthy controls.

Results

In the GMV meta-analysis, PBA compared to healthy controls showed: increased GMV in left cuneus cortex, left superior frontal gyrus, and right anterior cingulate cortex; decreased GMV in bilateral inferior temporal gyrus (ITG), left superior frontal gyrus, and right caudate nucleus. In the WMV meta-analysis, PBA showed: increased WMV in right fusiform gyrus and precuneus; decreased WMV in bilateral ITG, and right inferior frontal gyrus. In meta-regression analysis, the percentage of male PBA negatively correlated with decreased GMV of bilateral ITG.

Interpretation

PBA show widespread GMV and WMV alterations in the default mode network, visual recognition network, and salience network. These changes may be causally relevant to socialization difficulties and cognitive impairments. The meta-regression results perhaps reveal the structural underpinning of the cognition-related sex differences in PBA.

Altered functional network connectivity relates to motor development in children born very preterm

Individuals born very preterm (<32 weeks gestation) are at increased risk for neuromotor impairments. The ability to characterize the structural and functional mechanisms underlying these impairments remains limited using existing neuroimaging techniques. Resting state-functional magnetic resonance imaging (rs-fMRI) holds promise for defining the functional network architecture of the developing brain in relation to typical and aberrant neurodevelopment. In 58 very preterm and 65 term-born children studied from birth to age 12 years, we examined relations between functional connectivity measures from low-motion rs-fMRI data and motor skills assessed using the Movement Assessment Battery for Children, 2nd edition. Across all subscales, motor performance was better in term than very preterm children. Examination of relations between functional connectivity and motor measures using enrichment analysis revealed between-group differences within cerebellar, frontoparietal, and default mode networks, and between basal ganglia-motor, thalamus-motor, basal ganglia-auditory, and dorsal attention-default mode networks. Specifically, very preterm children exhibited weaker associations between motor scores and thalamus-motor and basal ganglia-motor network connectivity. These findings highlight key functional brain systems underlying motor development. They also demonstrate persisting developmental effects of preterm birth on functional connectivity and motor performance in childhood, providing evidence for an alternative network architecture supporting motor function in preterm children.